Adjustable mudline tubing hanger suspension system

Abstract

An adjustable mudline suspension system, including a tubing hanger having an exterior profile, a clamp having an inner profile to mate with the exterior profile of the tubing hanger, a biasing element to bias the clamp radially inward into an engaged position where the inner and exterior profiles are mated, and a piston to bias the clamp radially outward into a disengaged position where the inner and exterior profiles are not mated when hydraulically actuated. The weight of the tubing hanger is supported by the adjustable mudline suspension system when the interior profile of the clamp mates with the exterior profile of the hanger.

What is claimed is: 
     
       1. An adjustable mudline suspension system, comprising:
 a tubing hanger comprising an exterior profile; 
 a clamp comprising an inner profile to mate with the exterior profile of the tubing hanger; 
 a biasing element to bias the clamp radially inward into an engaged position where the inner and exterior profiles are mated; and 
 a hydraulically actuated piston to bias the clamp radially outward into a disengaged position where the inner and exterior profiles are not mated; 
 wherein the weight of the tubing hanger is supported by the adjustable mudline suspension system when the interior profile of the clamp mates with the exterior profile of the hanger. 
 
     
     
       2. The adjustable mudline suspension system of  claim 1  wherein the inner profile of the clamp comprises a plurality of stacked teeth. 
     
     
       3. The adjustable mudline suspension system of  claim 1  wherein the biasing element comprises a spring screw that exerts a downward spring force on the clamp. 
     
     
       4. The adjustable mudline suspension system of  claim 3  wherein the downward spring force is translated into a radially inward force as a result of a lower end of the clamp engaging a surface having a sloped profile. 
     
     
       5. The adjustable mudline suspension system of  claim 1  further comprising a housing containing a locking piston to prevent radially outward movement of the clamp. 
     
     
       6. The adjustable mudline suspension system of  claim 5  further comprising an outwardly biased lockring positioned in a radial recess of the locking piston, the lockring configured to engage a recess in the housing. 
     
     
       7. The adjustable mudline suspension system of  claim 6  wherein the recess in the housing has a sloped lower edge such that the lockring compresses in response to downward movement of the locking piston. 
     
     
       8. The adjustable mudline suspension system of  claim 7  wherein the lockring is outwardly biased such that the weight of the locking piston does not cause inward compression of the lockring as a result of the sloped lower edge. 
     
     
       9. The adjustable mudline suspension system of  claim 6  wherein the recess in the housing has a lower edge that is substantially perpendicular to the inner wall of the housing such that the lockring cannot compress in response to vertical movement of the locking piston. 
     
     
       10. The adjustable mudline suspension system of  claim 5  wherein the locking piston prevents the clamp from moving out of contact with the tubing hanger. 
     
     
       11. A method of installing an adjustable mudline suspension system, comprising:
 adjusting a tubing hanger to achieve a desired tension on a tubing string, the tubing hanger having an exterior profile; 
 setting the tubing hanger with a clamp to support and maintain the desired tension on the tubing string, the clamp having an inner profile; and 
 locking the clamp to the tubing hanger. 
 
     
     
       12. The method of  claim 11  wherein adjusting further comprises decoupling the clamp from the tubing hanger and raising or lowering the tubing hanger. 
     
     
       13. The method of  claim 12  wherein decoupling comprises hydraulically actuating the clamp into a disengaged position where the inner and exterior profiles are not mated. 
     
     
       14. The method of  claim 11  wherein setting further comprises:
 applying a mechanical biasing force to the clamp to bias the clamp inward toward the tubing hanger into an engaged position where the inner and exterior profiles are mated; and 
 releasing pressure from a hydraulic chamber, thereby permitting the clamp to move in response to the mechanical biasing force. 
 
     
     
       15. The method of  claim 14  further comprising applying the mechanical biasing force in a downward direction. 
     
     
       16. The method of  claim 15  further comprising translating the downward mechanical biasing force into a radially inward biasing force, thereby permitting the clamp to move inward toward the tubing hanger in response to the mechanical biasing force. 
     
     
       17. The method of  claim 16  further comprising a lower end of the clamp engaging a surface having a sloped profile. 
     
     
       18. The method of  claim 11  wherein locking further comprises actuating a locking piston, thereby causing a locking extension to be positioned between the clamp and a housing of the adjustable mudline suspension system and preventing the clamp from moving outward and out of contact with the tubing hanger. 
     
     
       19. The method of  claim 18  wherein when the locking extension is positioned between the clamp and the housing, the locking piston is prevented from moving vertically by an outwardly biased lockring engaging the housing.